Stockholm (AFP) – A teenager who attacked a goalkeeper on the pitch during a Swedish first division match acted because he was about to lose a bet he had placed on the game, the prosecution said Wednesday.

In the 90th minute of a match between Jonkoping and visiters Ostersund on August 15, the 17-year-old, who was clad in black and whose face was masked, stormed the pitch and assailed the away keeper, Aly Keita.

Keita was seen clutching his head as he returned to the changing rooms where he was tended to by medics, with the referee stopping the game which had been heading towards a 1-1 draw.

The teen told investigators “he had bet on a certain score in the match … and when the score was not what he had hoped for he acted out of disappointment,” prosecutor Pernilla Torsleff wrote in a statement.

The suspect, whose name has not been disclosed, was held in custody for one day but was then released.

Investigators said there were no other suspects, and the probe was expected to be wrapped up in September.

The young man was not a fan of either team, and hailed from Sodertalje, a suburb of Stockholm located around 300 kilometres (185 miles) from Jonkoping.

The attack raised a lot of questions in Sweden.

The state-run betting monopoly Svenska Spel said there were “rumours suggesting that a rigged match was the motive,” but it found no trace of suspicious betting.

Investigators did not say with whom the teenager placed the bet. The legal age of betting in Sweden is 18.

The Swedish Football Federation has meanwhile yet to decide what score to award the match. It could either confirm the 1-1 draw or grant Ostersund a 3-0 victory.